Since you suggested a rewrite of GHC's handling of proc-syntax, are there any opinions on integrating generalized arrows (Joseph 2014) in the process? I think they would greatly improve arrows! I don't know if I have the time to attempt this, but if I find
the time I would give it a try. Why wasn't this integrated while it was still actively developed?
The arrow stuff was added to GHC years before this thesis (which I had not seen before – thanks). I don’t have an opinions about
·
the desirability
·
the difficulty
of integrating generalised arrows.
You’re in the driving seat! By all means give it a go.
Simon
From: Jan Bracker [mailto:jan.bracker@googlemail.com]
Sent: 02 December 2016 15:58
To: Simon Peyton Jones <simonpj@microsoft.com>
Cc: Richard Eisenberg <rae@cs.brynmawr.edu>; ghc-devs@haskell.org; Ross Paterson (ross@soi.city.ac.uk) <ross@soi.city.ac.uk>; Henrik Nilsson <Henrik.Nilsson@nottingham.ac.uk>
Subject: Re: Help needed: Restrictions of proc-notation with RebindableSyntax
Simon, Richard,
thank you for your answer! I don't have time to look into the GHC sources right now, but I will set aside some time after the holidays and take a close look at what the exact restrictions on proc-notation are and document them.
Since you suggested a rewrite of GHC's handling of proc-syntax, are there any opinions on integrating generalized arrows (Joseph 2014) in the process? I think they would greatly improve arrows! I don't know if I have the time to attempt this, but if I find
the time I would give it a try. Why wasn't this integrated while it was still actively developed?
Best,
Jan
2016-11-29 12:41 GMT+00:00 Simon Peyton Jones <simonpj@microsoft.com>:
Jan,
Type checking and desugaring for arrow syntax has received Absolutely No Love for several years. I do not understand how it works very well, and I would not be at all surprised if it is broken in corner cases.
It really needs someone to look at it carefully, document it better, and perhaps refactor it – esp by using a different data type rather than piggy-backing on HsExpr.
In the light of that understanding, I think rebindable syntax will be easier.
I don’t know if you are up for that, but it’s a rather un-tended part of GHC.
Thanks
Simon
From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of Richard Eisenberg
Sent: 28 November 2016 22:30
To: Jan Bracker <jan.bracker@googlemail.com>
Cc: ghc-devs@haskell.org
Subject: Help needed: Restrictions of proc-notation with RebindableSyntax
Jan’s question is a good one, but I don’t know enough about procs to be able to answer. I do know that the answer can be found by looking for uses of `tcSyntaxOp` in the TcArrows module.... but I just can’t translate it all to source Haskell, having roughly 0 understanding of this end of the language.
Can anyone else help Jan here?
Richard
On Nov 23, 2016, at 4:34 AM, Jan Bracker via ghc-devs <ghc-devs@haskell.org> wrote:
Hello,
I want to use the proc-notation together with RebindableSyntax. So far what I am trying to do is working fine, but I would like to know what the exact restrictions on the supplied functions are. I am introducing additional indices and constraints on the operations. The documentation [1] says the details are in flux and that I should ask directly.
Best,
Jan
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